Previous weapon location systems (as used throughout this Application, the term "system" refers to a combination, in one embodiment, of hardware, software, and/or firmware which cooperates to perform one or more applications or functions) use either a purely or substantially singular acoustical detection apparatus or techniques or a purely or substantially singular optical detection apparatuses and/or techniques to locate the source of hostile weapon fire. Due to the problems and/or drawbacks associated with purely acoustical and purely optical detection techniques or substantially pure or singular techniques, the present invention combines the two concepts or technologies in order to utilize the advantages and substantially eliminate the disadvantages of each technology. Applicant has found that the combination of acoustical and optical detection mechanisms greatly enhances the overall detection capability of the system. Applicant believes that there was, prior to Applicant's invention, no and/or substantially little or substantially no motivation to combine these techniques in the manner done by Applicant.
Acoustical detection systems generally determine the direction and/or location of hostile weapon fire by measuring and/or calculating the arrival of "sound" or acoustic energy generated by the hostile fire by the use of generally and equally spaced microphones formed or placed in a microphone array. Most prior acoustical hostile weapons fire detection and/or location systems are characterized by generally omnidirectional detection, only moderate accuracy and a substantially minimal false alarm rate. While such prior acoustic systems provide useful information for many applications, purely and/or substantially pure acoustical detection systems are not entirely appropriate for certain applications, such as applications involving the detection of the firing of supersonic and/or substantially supersonic projectiles. That is, supersonic projectiles arrive to the target prior to the arrival of the acoustic energy generated by the firing of these supersonic projectiles. Thus, an immediate counter-measure launch, necessary to destroy the incoming supersonic missiles, is generally not possible when a purely or singular acoustical system is used to detect the presence and/or location of such supersonic enemy fire. Additionally, it is well known that acoustic detection systems generally have a fairly large error in the determination of the location of the hostile weapon. In the past, this was not really a problem since offensive countermeasures which were used to destroy the hostile weapon usually comprised one or more missiles which destroyed a relatively large area. This wide area of destruction mostly and adequately compensated for the errant location data provided by the acoustic detection and/or location systems. However, war has changed. Oftentimes snipers, located within relatively densely populated areas are now encountered. Hence, large destructive countermeasures, necessary to compensate for errant location calculations, are generally not appropriate since they might hurt or kill many innocent people and destroy many valuable and historic buildings and/or other structures.
Optical detection systems generally determine the location and/or direction of hostile weapons fire by observing and/or sensing the position of the optical energy released or generated when a weapon is discharged. Most optical systems are characterized by relatively high accuracy, relatively high amounts or levels of false alarms and a rather limited field of view. Purely optical systems are also of rather limited value in some ambient light conditions where distinguishing the flash of a weapon from false flashes or other types of visible radiation is difficult. Purely optical systems are also of rather limited value where a weapon is obstructed or outside of the optical system's field of view. Hence, these prior optical detection systems were used only in very few specific applications, mainly due to their relatively high false alarm rate. Heretobefore, only one type of these systems was used to determine/calculate the location of adverse weaponry. No one, prior to Applicant's discovery and/or invention, had realized the benefit of combining these two types of dissimilar systems in a manner which would overcome the drawbacks of each of these systems and provide a more robust system.
That is, Applicant was the first to realize that great accuracy and usefulness could be achieved by first using an acoustic system to determine the general location of the hostile weapons fire, a function that such prior acoustic systems performed relatively well, and then using an optical system or referring to or reviewing captured optical data in order to further refine the location within the field established by the acoustic system. In this manner, the relatively notorious "false alarms" associated with the optical systems could be minimized since the optical data only from the field of view formed or "fixed" by the acoustical technique would be reviewed. Moreover, the concomitant use of optical system data could allow even supersonic projectiles to be detected. This new combined system thus allows great accuracy which is necessary when detecting hostile weapons fire in cities and other areas in which greatly destructive missile counteroffensive apparatuses cannot be used.
There is therefore a need for, and it is a principal object of this invention to provide, a weapon and/or hostile weapons firing location and localization system which overcomes the aforementioned drawbacks of the prior substantially purely acoustical and substantially purely optical detection systems and which, in fact, combines the advantages and the techniques of the two systems to achieve a system characterized by general omnidirectional detection, a relatively low false alarm rate, relatively high accuracy and relatively immediate counter-measure capability. In essence, Applicant has discovered that one may utilize the accuracy of infrared systems in combination with "gross" type location data specified by the acoustic systems to provide a very desirable system. As used in this Application, the terms "location" and "localization" each mean the location of an entity (e.g. hostile weapons fire) as well as the processes to locate the firing entity. Thus, these words may be used interchangeably.